Prostheses for implantation in blood vessels or other similar organs of the living body are, in general, well known in the medical art. For example, prosthetic endovascular grafts constructed of biocompatible materials have been employed to replace or bypass damaged or occluded natural blood vessels. In general, endovascular grafts include a graft anchoring component that operates to hold a tubular graft component of a suitable graft material in its intended position within the blood vessel. Most commonly, the graft anchoring component is one or more radially compressible stents that are radially expanded in situ to anchor the tubular graft component to the wall of a blood vessel or anatomical conduit. In addition, the stents also have a patency function in that the stents keep the graft open and radially expanded along portions of the graft that are not necessarily opposed to the vessel wall, i.e., along portions of graft disposed within an aneurysm sac. Thus, endovascular grafts are typically held in place by mechanical engagement and friction due to the apposition forces provided by the radially expanded stents.
Grafting procedures are also known for treating aneurysms. Aneurysms result from weak, thinned blood vessel walls that “balloon” or expand due to aging, disease and/or blood pressure in the vessel. Consequently, aneurysmal vessels have a potential to rupture, causing internal bleeding and potentially life threatening conditions. Grafts are often used to isolate aneurysms or other blood vessel abnormalities from normal blood pressure, reducing pressure on the weakened vessel wall and reducing the chance of vessel rupture. As such, a tubular endovascular graft may be placed within the aneurysmal blood vessel to create a new flow path and an artificial flow conduit through the aneurysm, thereby reducing if not nearly eliminating the exertion of blood pressure on the aneurysm.
In general, rather than performing an open surgical procedure to implant a bypass graft that may be traumatic and invasive, endovascular grafts which may be referred to as stent-grafts are preferably deployed through a less invasive intraluminal delivery procedure. More particularly, a lumen or vasculature is accessed percutaneously at a convenient and less traumatic entry point, and the stent-graft is routed through the vasculature to the site where the prosthesis is to be deployed. Intraluminal deployment is typically effected using a delivery catheter with coaxial inner and outer tubes or shafts arranged for relative axial movement. For example, a self-expanding stent-graft may be compressed and disposed within a distal end of an outer shaft or sheath component of the delivery catheter distal of a stop fixed to an inner shaft or member. The delivery catheter is then maneuvered, typically tracked through a body lumen until a distal end of the delivery catheter and the stent-graft are positioned at the intended treatment site. The stop on the inner member is then held stationary while the sheath component of the delivery catheter is withdrawn. The stop on the inner member prevents the stent-graft from being withdrawn with the sheath component. As the sheath component is withdrawn, the stent-graft is released from the confines thereof and radially self-expands so that at least a portion of it contacts and substantially conforms to a portion of the surrounding interior of the lumen, e.g., the blood vessel wall or anatomical conduit.
In some applications, the blood vessel wall or anatomical conduit in which the stent-graft is to be implanted is highly curved or angled. There is a need in the art for improved stent-grafts that are kink-resistant in order to substantially conform to highly curved or angled anatomy. Improved flexibility and patency results in improved hemodynamic blood flow through highly angulated stent grafts.